1. Technical Field
The present invention relates to an electrophotographic image forming apparatus and image forming method for developing an image using a liquid developer containing a toner and a carrier liquid, and squeezing the carrier liquid held by the latent image carrier following the development stage.
2. Background Technology
Various wet image forming apparatus have been proposed in which a latent image is developed using a high-viscosity liquid developer in which a solid toner has been dispersed in a liquid solvent, and the electrostatic latent image is rendered visible. The developer used in a wet image forming apparatus includes a solid component (toner particles) suspended in a high-viscosity organic solvent (carrier liquid) with electrical insulating properties, such as silicone oil, mineral oil, or cooking oil. The toner particles are very fine particles having a particle size of about 1 μm. The use of fine toner particles enables the wet image forming apparatus to produce higher quality images than a dry image forming apparatus that uses powdery toner particles having a particle size of about 7 μm.
In the image forming apparatus using a liquid developer containing a toner and a carrier liquid, the excess carrier liquid from the liquid developer developed on the latent image carrier must be removed. The excess toner (fogging toner) adhering to the non-image portions of the latent image carrier also must be removed. It has thus been proposed that the surplus developer such as excess carrier liquid and excess fogging toner be removed using a squeeze roller rotatably making contact with the latent image carrier in the direction opposite that of the rotational direction of the latent image carrier (the direction of both circumferential velocities being the same).
A removing member for removing the surplus carrier from the latent image carrier has been disclosed in Patent Citation 1 as such a squeeze roller. As disclosed in Patent Citation 2, wasteful consumption of the toner and the carrier is reduced and abnormal electrical discharges with the latent image carrier are avoided by controlling the engagement/disengagement operation of the sweep roller, the timing of the disengagement operation, and the bias voltage application operation. A two-stage surplus carrier removing means is disclosed in Patent Citation 3 that prevents disturbance of the toner particles in the image portion by using different revolution speeds, roller diameters and roller hardnesses in the relation between the first stage and the second stage.    Japanese Patent Application Publication No. 2002-278303 (Patent Citation 1) is an example of the related art.    Japanese Patent Application Publication No. 2002-287516 (Patent Citation 2) is an example of the related art.    Japanese Patent Application Publication No. 2009-98396 (Patent Citation 3) is an example of the related art.